We report on an investigation of the local structure and vibrational dynamics in the brownmillerite-based proton conductors Ba₂In_1.85M_0.15O₆H₂ with M = In, Ga, Sc and Y. The aim is to determine the effect of the cation (M) substitution on the local coordination environment of the protons. The techniques used are infrared spectroscopy and inelastic neutron scattering. The materials are characterized by two main types of proton sites, denoted as H(1) and H(2), which are featured by different local structures. We establish that the relative population of these two proton sites varies as a function of M. Specifically, it is found that, with respect to Ba₂In₂O₆H₂, the relative population of H(1) protons increases upon the substitution of In with any of the three different cations. The strongest effect is observed for M = Ga and Sc, whereas the effect observed for M = Y is minor. This new insight motivates efforts to unravel the mobility of the two types of protons, since then cation modification would offer a rational route for improving the proton conductivity of these types of materials.

我们报告了对基于棕褐色矿物的质子导体Ba ₂ In _1.85 M _0.15 O ₆ H ₂中M = In，Ga，Sc和Y的局部结构和振动动力学的研究。目的是确定阳离子的影响（M）替代质子的局部配位环境。使用的技术是红外光谱法和非弹性中子散射。这些材料的特征在于质子位点的两种主要类型，分别表示为H（1）和H（2），它们具有不同的局部结构。我们确定这两个质子位点的相对种群随M的变化而变化。具体而言，发现对于Ba ₂ In ₂ O ₆ H ₂，当用三种不同阳离子中的任一种取代In时，H（1）质子的相对种群增加。对于M＝ Ga和Sc，观察到最强的作用，而对于M＝ Y，观察到的作用很小。这一新见解激发了努力来揭示两种类型的质子的迁移率，因为从那时起阳离子改性将为改善这类材料的质子传导性提供一条合理的途径。